The present invention relates generally to a device and method for breaking up encrusted materials. More particularly, the invention pertains to a novel device and method for uniformly particulating material such as a soil sample.
Frequently, materials which tend to conglomerate must be broken into particles of workable size before utilization. For example, chemicals, fertilizers, soil, and the like can form into dense, irregularly caked masses under conditions of high humidity and/or compression. Before such materials can be utilized, the conglomerations therein must be reduced to particles of the desired size. Various forms of sifting devices have heretofore been employed to accomplish this function. Of course, small clusters of relatively loosely packed materials can be broken up by hand. However, the sifting devices of the prior art are generally gravity fed and are thus incapable of breaking up clusters of tightly packed materials. As a consequence, the prior art approaches to this problem are characterized by waste and ineffectivity. There is thus a need for a device capable of conditioning even tightly packed conglomerations into particles of workable size.
For example, particulated soil is necessary for the various soil tests which must be conducted in the construction of earth works projects. Such earth works projects include foundations, embankments, roads, fills, dykes, levees, dams, and the like. Depending upon the size of the project, samples from one or more locations are taken so that the soil can be analyzed for moisture content, density, compaction, as well as other soil properties. Of course, uniform soil samples must be taken to obtain accurate test results. However, the problem of obtaining uniform soil samples is complicated by the fact that each sample is a distinct composition of sand, clay, minerals, and gravel or rock. Before testing, each soil sample must first be processed into particles or flakes of a uniform size, and any rock or gravel must be segregated therefrom. Uniform soil testing procedures have been established, one such procedure being the Rapid Method of Construction Control for Embankments of Cohesive Soil, as set forth in "Engineering monograph No. 26" printed by the U.S. Department of the Interior, Bureau of Reclamation. This testing procedure can be implemented by hand processing approximately twenty pounds of soil at field moisture through a No. 4 sieve, which is a difficult and time consuming process especially when CH or CL type material is involved. Heretofore there has not been available a mechanical apparatus for performing this function in accordance with such established requirements.
The present invention comprises a device and method for particulating materials which overcomes the foregoing and other difficulties long since associated with the prior art. In accordance with the broader aspects of the invention, a drum is provided with a cylindrical wall of screen or grating with a predetermined mesh size. The drum is preferably mounted for rotation about an axis offset from the longitudinal axis thereof. During rotation of the drum, the conglomerated materials are forced through the wall of the drum to reduce the materials to particles of the desired size. During the process, unbreakable matter is separated from the final particulated matter. The invention is particularly adapted for breaking up soil samples including hard, relatively large lumps of dense, tightly packed soil.
In accordance with more specific aspects of the invention, a drum is mounted for rotation about a substantially vertical axis offset from the longitudinal axis of the drum. The drum is adjustably secured between hubs to provide for variable eccentricity. A motor is employed to effect rotation of the drum through a chain and sprockets. The cylindrical wall of the rotating drum comprises a screen. An arcuate wall in positioned in spaced relationship to the periphery of the drum. The forward end of the arcuate wall is pivotally secured at a point adjacent to the rotating drum. The trailing end of the arcuate wall engages another wall and includes a lever arm connected to a weight. Preferably, the lever arm is extendible to provide the desired leverage forcing the arcuate wall toward the drum.
The material to be reduced is placed between the rotating drum and the arcuate wall, which then crowds the material into contact with the screen. A ratchet mechanism is utilized to prevent backlash of the arcuate wall as a consequence of the eccentricity of the rotating drum. The material is thus sheared as it is forced through the periphery of the drum to effect granulation. The workable particles of material are then collected beneath the drum for utilization. If desired, a row of fingers and/or a brush can also be mounted for engagement with the rotating drum to loosen any material clogged in the screen.